Peripheral blood in the circulatory system of a human is comprised principally of red blood cells, erythrocytes, and white blood cells, leukocytes. The function is leukocytes and their clinical relevance has generated great interest in the scientific community. The family of white blood cells is comprised of neutrophils, monocytes, eosinophils, basophils and lymphocytes, which have numerous subsets.
Neutrophils, monocytes, eosinophils and basophils are known as phagocytes because their primary function in the human immune system is to phagocytose or ingest bacteria and other microorganisms. These cells are produced in the bone marrow of a human. However, each of these phagocytes has different functions and behaves as a related but separate system. Although originating in bone marrow, phagocytic cells do enter into and circulate in peripheral blood.
The general function of the phagocyte system is to achieve phagocytosis of substances recognized as foreign and to assist in the development of an immune response against a foreign substance. Neutrophils are very efficient as a phagocyte for bacteria that have been coated with an antibody and not so efficient for bacteria without antibody coating. The major function of the neutrophil is to prevent invasion by pathogenic microorganisms by localizing and killing them after their invasion. In order to successfully attack an invading microorganism, the neutrophil will exit the peripheral blood, migrate to the tissue area of the infection's start and then, recognize, kill and digest the microorganism.
The neutrophil is the most common cell in bone marrow and the most common leukocyte in peripheral blood. One microliter of a normal whole blood sample includes, on average, 5.times.10.sup.3 leukocytes of which 3,075 are neutrophils, 150 are eosinophils, 25 are basophils, 250 are monocytes and 1500 are lymphocytes. The departure from the normal concentration of neutrophils in peripheral blood has recognized clinical relevance. Thus increased concentrations sometimes termed "neutrophilia", may evidence certain disease or physical conditions while decreased concentrations of neutrophils in peripheral blood, sometimes termed "neutropenia" would have different clinical relevance. For instance, an absolute neutrophil count of less than 500 cells per microliter is a life-threatening condition since a patient with such an abnormal count is highly susceptible to life threatening bacterial or fungus infections. Neutropenia may result from cytotoxic drugs, such as administered in treatment of cancer or leukemia. There are numerous congenital and acquired diseases associated with abnormalities of neutrophil function, as well. Assay of neutrophils in peripheral blood is an important part of a total leukocyte count.
This invention provides a novel monoclonal antibody to an antigenic site on the surface of a neutrophil. Such a monoclonal antibody can perform a variety of different functions depending on how it is used, i.e., how labelled, such as with fluorescein or Biotin, for instance, or conjugated to a bead or microsphere, magnetic or non-magnetic, for instance, for identification and enumeration of human neutrophils. The advantages to be derived from such a specific monoclonal antibody clearly are desirable.